Make SkPictureShader and SkPictureImageFilter use const SkPictures

src/effects/SkPictureImageFilter.cpp

 /*
  * Copyright 2013 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPictureImageFilter.h"
 #include "SkDevice.h"
 #include "SkCanvas.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkValidationUtils.h"
 
-SkPictureImageFilter::SkPictureImageFilter(SkPicture* picture)
+SkPictureImageFilter::SkPictureImageFilter(const SkPicture* picture)
   : INHERITED(0, 0),
     fPicture(picture),
     fCropRect(SkRect::MakeWH(picture ? SkIntToScalar(picture->width()) : 0,
                              picture ? SkIntToScalar(picture->height()) : 0)) {
     SkSafeRef(fPicture);
 }
 
-SkPictureImageFilter::SkPictureImageFilter(SkPicture* picture, const SkRect& cropRect)
+SkPictureImageFilter::SkPictureImageFilter(const SkPicture* picture, const SkRect& cropRect)
   : INHERITED(0, 0),
     fPicture(picture),
     fCropRect(cropRect) {
     SkSafeRef(fPicture);
 }
 
 SkPictureImageFilter::~SkPictureImageFilter() {
     SkSafeUnref(fPicture);
 }
 
@@ skipping 58 matching lines @@
     offset->fY = bounds.fTop;
     return true;
 }
 
 bool SkPictureImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
                                           SkIRect* dst) const {
     *dst = src;
     return true;
 }